1. Field of the Invention
The present invention relates to a correction device for correcting acceleration data provided based on output from an acceleration sensor which detects the acceleration of a mobile body, by determining via calculation an offset value of the acceleration sensor and correcting the output based on the offset value, correction method therefor, correction program therefor, recording medium for recording the program, and navigation guide device.
2. Description of Related Art
The conventional well-known system for guiding the navigation of a mobile body such as a motor vehicle, aircraft and ship includes navigation guide systems. The navigation guide system obtains information regarding the current position of a mobile body, relates the current position with map information, and plots the current position on a map. Specifically, the navigation guide system determines the current position of a mobile body, its travel distance and its heading based on a radio signal received from an artificial satellite, and on signals provided by various sensors attached to the mobile body, and informs the mobile body of its driving condition by displaying the acquired data on a map.
A simple conventional navigation guide system uses an acceleration sensor for obtaining information regarding the driving condition of a mobile body. The acceleration sensor is configured such that its output changes in accordance with the change of the acceleration of the mobile body. The system in question checks whether there is any output from the acceleration sensor when the mobile body remains motionless,
As described above, with the conventional navigation guide system, to obtain an offset value of an acceleration sensor, it is necessary to keep a mobile body to which the sensor is attached motionless on a horizontal plane and to read output from the sensor, which requires complicated operation. Moreover, the acceleration sensor may undergo variations as a result of temperature change during the prolonged use of a mobile body to which the sensor is attached, as described above. Thus, to ensure the rightness of the acceleration data acquired based on output from the acceleration sensor, it is necessary to often check the sensor and obtain a right offset value during the prolonged use of the mobile body, which requires complicated operation. Such an operation when performed often may hinder the proper operation of the mobile body. Moreover, if owing to a certain situation, checking of the sensor were impossible, the sensor would be left unchecked, and the navigation guide system could not achieve the proper navigation guide assigned to it.